Final answer:
The suffix -emesis means 'vomiting', which is the forceful expulsion of stomach contents through the mouth, often caused by irritants like viruses or bacteria.
Step-by-step explanation:
The suffix -emesis refers to vomiting. Therefore, the correct answer to what the suffix -emesis means is 'a. vomiting'. When associated with medical terminology, this suffix indicates a condition related to the forceful expulsion of stomach contents through the mouth. For instance, if you come down with the flu, you might experience emesis, which is caused by various irritants affecting the digestive tract such as viruses, bacteria, emotional stress, and sometimes more visceral responses to sights, or food poisoning.